ASPX: FileUpload limit IN ADVANCE the size and type of files.

I’m relative new to ASPX. I have a page on which a user could upload a file. I want to limit the user by type /image/ and by size (3 MB), but I want do this BEFORE the user post the file. I use a standard FileUpload control, not upload the file in additional page, I upload it on the main Submit button - look the page:http://demo.asp2.eu/Register_bMA.aspx?langID=EN

I put a code in my Submit button for that purpose, but it look when the user select a big file the code AT all do not goes here – it get server error message. I want to stop user BEFORE he start uploading file with 200 MB by mistake /there is change for such mistake, no body read the message what should be uploaded here and it may start upload video file. /

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

Or may be to use AJAX FileUpload control or other third part library? Anyway, i use AJAX library ... i want to put a control which to make validation BEFORE real upload of the file. This is common task, how it is usually solved?

It is a possible solution, could you please help me with more detail how to apply it? I have a simple form with Submit button and C# code after it, i think I should replace and first call this JavaFunction, but I need help for right syntacs

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Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

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